DEVICE TO PUNCH PLASTER TAPES

Abstract: Device to punch plaster tapes, wherein an adhesive support layer and a layer of protective material are present, including an hollow rotating tubular body (1), having on the surface thereof a plurality of drilled radial socket punches (6, 6a), realized in a single body with the rotating body (1) or, alternatively, with removable sectors (12) thereof, equipped with cutting edges (7, 7a) at the hole mouth and with small chips stacks, inside said holes, cooperating in removing chips of protective material and contrast and drive means (2), the plaster tape (3) being provided passing between said rotating body (1) and said contrast means (2) synchronously progressing with the rotating body (1), said cutting edges and said contrast means being kept spaced.

Description: DEVICE TO PUNCH PLASTER TAPES The present invention deals with a device to punch plaster tapes. it is well known that the plaster surface must be generally equipped with perforations to allow the skin to perspire. It is common to produce plasters starting from tape reels including a first layer of support material, equipped with an adhesive side, and a second layer of protective material, for example siliconated paper, that can be easily separated from the first layer, commonly known as "liner". The above-said layers are coupled either through the adhesive present on the first layer, or through other means, leaving, in this latter case, the adhesive surface of the first layer free. After punching, the two layers are separated and subjected to other working steps. In order to obtain the desired punching, two methods can be used, that can be respectively defined as hot method and cold method. The term hot method deals with the tape punching technique that provides a slight penetration of heated needles that melt the adhesive support, if thermoplastic, and preserve the "liner" substantially integral, thus allowing it to be used again. However, through this method, scarcely visible holes are obtained, that can be unequal, irregular and wrinkled due to the uneven thermoplastic melting when the distance from the hot needle point increases. The term cold method deals with the tape punching technique that provides the use of cutting means that engrave the tape, generating circular holes and removing chips of material including both plaster and "liner", that therefore, being riddled as a result, is usually rejected. Furthermore, this method is usually carried out through cutting means with respect to a hard contrast surface that therefore wears them and forces the cutting surfaces to be frequently replaced and sharpened. Therefore, these surfaces are generally obtained through removable bodies to make their replacement easier. These embodiments however are complex and usually allow obtaining punching densities that are not greater than 10 holes per cm . Object of the present invention is providing a device to generate holes in the plaster surface that allows cold operations, without appreciably engraving the "liner", keeping it reusable, and that allows obtaining at the same time holes that are even and free from flaws. Another object of the present invention is obtaining a device that allows strongly increasing the cutting surface life. These and other objects are obtained through the device to punch plaster tapes, wherein an adhesive support li./er and a layer of protective material are present, including an aollow rotating tubular body having on the surface thereof a plurality of drilled socket punches, communicating with the rotating body recess, radially arranged at the same distance from the rotation axis of the rotating body, equipped with a cutting edge at the hole mouth and contrast and drive means cooperating with said rotating body, the plaster tape being provided passing between said rotating body and said contrast means synchronously progressing with the rotating body, the device being characterized in that: said socket punches form a single body with the rotating body or, alternatively, with removable sectors thereof; the cutting edges of socket punches and contrast means are kept spaced, said distance being not greater than the thickness of the layer of protective material; the hole inside the socket punches shows, starting from the cutting edges, a section whose diameter and length are respectively not greater and not lower than the cutting edge diameter; small stacks of chips are present inside the socket punch holes to cooperate, when removing chips of protective material, with the cutting edges and the hole inside the socket punches. A second embodiment of the device provides the stiff connection of the socket punches into suitable seats provided in the rotating body, or alternatively, in suitable seats provided in removable sectors of said rotating body. A preferred, but not exclusive, embodiment of the invention will now be described with reference to the enclosed drawings in which: Fig. 1 is a side view, partially in section, of the device; Fig. 2 is a section of a part in the device in Fig. 1; F;'.~. 3 is an axial view, partially in section, of the device in Fig. 1; Fig. 4 is a partial view of a part in a second embodiment of the device; Fig. 5 is a partial view of a part in a third embodiment of the device. With reference to Figure 1, the device of the present invention includes a punching cylinder 1, equipped with an internal recess 9, on which there are assembled, through screws 13, 13a, the removable members 12 wherein, in a single body, the radial cone-shaped socket punches 6, 6a equipped with the cutting edges 7, 7a are formed. Said cutting edges 7, 7a are kept spaced with respect to the surface of the smooth contrast cylinder 2 in order to allow the socket punches 6, 6a to penetrate into the plaster tape 3 till they reach the "liner" layer 11, without however completely punching it, through the adhesive support layer 10. For this purpose, as detailed in figure 2, the distance "d" between the cutting edges 7 and the smooth surface of the contrast cylinder 2 is kept not lower than 50% of the thickness of the "liner" layer 11. During rotation of the cylinder 1, therefore, punching of the first layer 10 and the sole engraving of the second layer 11 are carried out followed by the removal of a chip of material coming from the first layer 10 only. The chips 14, 14a, 14b thus formed adhere one on top of the other due to the adhesive, both if it is facing the layer 11 and if it is on the free surface of the layer 10 and is therefore facing the socket punch 6. The small stacks of chips therefore cooperate with the surface of the hole (8), inside the socket punch, in punching the tape, making removal of the following chips easier during rotation of the cylinders 1 and 2. Said rotation occurs in the direction shown by arrows 4 and 5, and favours the tape translation in the direction shown by arrow 15. The hole 8 of the socket punch 6 shows a first section, next to the cutting edges, whose diameter and length are respectively not greater and not lower than the diameter of the cutting edge and a second section, facing the cylinder recess, whose diameter is greater than the first section. In other embodiments that provide the use of highly resistant steels, the hole inside the socket punches shows a single section directly communicating with the internal recess 9 of the punching cylinder 1. With reference to Figure 3, the punching cylinder 1 is further equipped with "shoulders" 16, 16a opposed to other contrast "shoulders" 17, 17a provided on the cylinder 2, suitable to keep cylinders 1 and 2 spaced, that are counter-rotating by means of the mating of gears 18 and 19. The cylinder 1 can further by equipped with a side opening 20 and with a cone-shaped duct 21 which communicates with a source of compressed air, not shown, adapted to make chips removal easier. The described device is suitable to operate with the maximum accuracy and to drill very small holes (from 0.5 mm to 1.0 mm in diameter) and closely spaced (20 holes per cm 2 ). Furthermore, the chips are completely removed and are not scattered on the tape being worked making it unusable. In order to obtain these results, in addition to a very accurate adjustment of the distance between the cylinders, that can be obtained, as described, by means of the "shoulders", it is further necessary that the short elastic stacks of layered chips be present inside the socket punch holes. Said short stacks, upon start-up of the device, can be preformed by punching a single-layer tape, with adhesive support only, and by using as contrast means a cylinder made of wood or other material against which the cutting edges of the socket punches can operate without being damaged. With reference to Figure 4, the socket punch 6' is stiffly connected, for example by pressure and with the help of welding means, in circular seats 22 provided in the body of cylinder 1'. Alternatively, the socket punches can be stiffly connected, as described in the previous paragraph, into suitable seats formed in the removable members 12. With reference to Figure 5, the socket punch 6' ' is equipped with external thread adapted to allow it to be screwed into threaded seats 23 provided in the body of cylinder 1 ' ' . Alternatively, the socket punches can be screwed, as described in the previous paragraph. into suitable threaded seats formed in the removable members 12.

Claims: CIAIMS 1. Device to punch plaster tapes, wherein an adhesive support layer and a layer of protective material are present, including an hollow rotating tubular body having on the external surface thereof a plurality of drilled socket punches, communicating with the rotating body recess, equipped with a cutting edge at the external hole mouth, radially arranged at the same distance from the rotation axis of the rotating body, and contrast and drive means cooperating with said rotating body, the plaster tape being provided passing between said rotating body and said contrast means synchronously progressing with the rotating body, characterized in that: said socket punches form a single body with the rotating body or, alternatively, with removable sectors thereof; the cutting edges of socket punches and contrast means are kept spaced, said distance being not greater than the thickness of the layer of protective material; the hole inside the socket punches shows, starting from the cutting edges, a section whose diameter and length are respectively not greater and not lower than the cutting edge diameter; small stacks of chips are present inside the socket punch holes to cooperate, when removing chips of protective material, with the cutting eαges and the hole inside the socket punches. 2. Device to punch plaster tapes, wherein an adhesive support layer and a layer of protective material are present, including an hollow rotating tubular body having on the external surface thereof a plurality of drilled socket punches, communicating with the rotating body recess, equipped with a cutting edge at the external hole mouth, radially arranged at the same distance from the rotation axis of the rotating body, and contrast and drive means cooperating with said rotating body, the plaster tape being provided passing between said rotating body and said contrast means synchronously progressing with the rotating body, characterized in that: said socket punches are stiffly connected into suitable seats provided in the rotating body, or alternatively into suitable seats provided in removable sectors of said rotating body; the cutting edges of socket punches and contrast means are kept spaced, said distance being not greater than the thickness of the layer of protective material; the hole inside the socket punches shows, starting from the cutting edges, a section whose diameter and length are respectively not greater and not lower than the cutting edge diameter; small stacks of chips are present inside the socket punch holes to cooperate, when removing chips of protective material, with the cutting edges and the hole inside the socket punches. 3. Device as claimed in claim 2, characterized in that said socket punches are stiffly connected into said seats by pressure and with the help of welding means. 4. Device as claimed in claim 2, characterized in that said seats provided in the rotating body or alternatively in removable sectors thereof, show a threaded surface and in that said socket punches are also externally threaded. 5. Device as claimed in claim 1 or 2, characterized in that said tubular rotating body is realized by means of a hollow cylinder equipped with spacing reliefs or shoulders adapted to avoid contact of the cutting edges of the socket punches with the contrast means when punching. 6. Device as claimed in claim 5, characterized in that the contrast means are realized by means of a cylinder equipped with spacing shoulders cooperating with said opposed spacing shoulders 5 provided in the hollow cylinder, said cylinders being counter-rotating with respect to parallel axes through peripheral gears. 7. Device as claimed in claim 5, characterized in that the distance between said cutting edges and . ° said contrast means is not lower than 50% of the thickness of the layer of protective material. 8. Device as claimed in claim 5, characterized in that the chips removed when punching the tape include a layer of adhesive support only. 5 9. Device as claimed in claim 5, characterized in that said hollow cylinder shows an open side to eject the chips deriving from punching and a side in which a hole is present that widens inside the cylinder in a cone-shaped duct, said hole 0 communicating with a source of compressed air to eject the chips. 10. Device as claimed in claim 1 or 2, characterized in that the arrangement of said socket punches on said tubular body is adapted to 5 produce in said tape a plurality of holes grouped in cyclically repeating configurations. 11. Device as claimed in claim 1 or 2, characterized in that the hole inside the socket punches shows a section, facing the rotating body recess, whose diameter is greater than the section facing the cutting edges.

Inventors: DOTTA ANGELO, DOTTA, ANGELO
Applicants: DOTTA ANGELO, PLASTOD SPA, DOTTA, ANGELO, PLASTOD S.P.A.
Application year: 1994
Main classification: B26D3
IPC codes: A61F13, B26D3, B26D7, B26F1